Postsurgical Temporary Epicardial Pacing: Electrophysiological Implications of Contemporary Pacing Lead Designs.

Background: Despite advancements in postoperative temporary epicardial pacing leads, sensing malfunction can still happen. Oversensing presents as inappropriate inhibition of pacing (a major concern for pacemaker-dependent patients), whereas undersensing may lead to an extremely rare complication of ventricular fibrillation from R on T. The single-lead and dual-lead configurations have key structural differences related to the size of the bipole electrodes and the spacing between them. We assessed how this affects the sensing function. Methods: Five porcine studies were conducted using open chest and Langendorff models. We used 2 pacing wire configurations and compared the sensed electrograms. We compared a newer single-lead configuration (small, closely spaced electrodes) with a dual-lead (large, widely spaced) configuration. The primary outcome was the amplitude of the R wave. Secondary outcomes were the relative size of the T wave and the effect of sampling frequency and low-pass filtering. Results: The sensed QRS was significantly larger in the widely spaced, larger electrodes when compared with closely spaced, smaller electrodes across all sampling frequencies and filter settings (6.9-29.7 mV vs 1.7-8.6 mV, Conclusions: The smaller, closely spaced electrodes detect a relatively small QRS and a larger T wave, leading to a narrower safety window and an increased risk of sensing malfunction (Central Illustration). To avert catastrophic consequences, the electrophysiologic implications of new temporary pacing wires must be considered during postoperative care.